Increased diversity of Phytophthora species in Fraser fir Christmas tree plantations in the Southern Appalachians

Abstract

Phytophthora root rot (PRR) disease afflicts significant economic losses to the Fraser fir Christmas tree industry. In previous surveys conducted in 1972 and from 1997 to 1998 in North Carolina, the incidence of PRR was approximate to 9.5% with Phytophthora cinnamomi identified as the predominant causal species isolated from infected roots of Fraser fir. Due to increased use of out-of-state planting stock since 2000, we suspected increased diversity of Phytophthora species. During 2014, we surveyed Fraser fir Christmas tree plantations in the Southern Appalachians of North Carolina, Tennessee and Virginia to determine the occurrence of pathogenic root-rotting species of Phytophthora. A weighted sampling strategy based on Christmas tree acreage was deployed to collect symptomatic Fraser fir roots from 103 commercial production fields in 14 counties. Six species of Phytophthora were isolated from infected roots sampled from 82 sites in 13 counties. Phytophthora cinnamomi, P. cryptogea and P. pini represented 70.3%, 23.1% and 1.1% of the 91 isolates. Phytophthora citrophthora, P. europaea and P. sansomeana accounted for the remaining 5.5% of the isolates and have not been identified in previously published Fraser fir surveys conducted in the region. The pathogenicity of P. citrophthora on Fraser fir was confirmed based on completion of Koch's postulates.

Keywords

Abies fraseri; North Carolina; Phytophthora cinnamomi; root rot; survey

Published in

Scandinavian Journal of Forest Research
2017, volume: 32, number: 5, pages: 412-420
Publisher: TAYLOR & FRANCIS AS

SLU Authors

• Rönnberg, Jonas

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network

UKÄ Subject classification

Forest Science

Publication identifier

• DOI: https://doi.org/10.1080/02827581.2016.1265144

Permanent link to this page (URI)

https://res.slu.se/id/publ/83512